The subject matter described herein relates to electrical connectors that mate with pluggable modules having circuit boards.
Some electrical connectors include a socket that receives a mating edge of a circuit board within a pluggable module. The mating edge provides an interface between the pluggable module and one or more rows of electrical contacts that extend within the socket of the electrical connector. The circuit board includes contact pads arranged along the mating edge on one or both opposite sides of the circuit board. The electrical connector includes a pair of opposite rows of electrical contacts extending within the socket that engage the contact pads on corresponding sides of the circuit board. The electrical contacts are signal contacts and ground contacts. The signal contacts convey differential signals, while the ground contacts provide shielding and grounding to the transmitted signals.
The ongoing trend of smaller connectors transmitting more data and operating at faster data rates leads to continuing increases in the density of the signal contacts. The density of signal contacts may be increased by reducing the spacing between adjacent contacts. Reducing the spacing presents mechanical design issues and electrical operating issues. For example, in some electrical connectors the signal conductors are over-molded with a dielectric material to provide electrical insulation and support to the signal conductors. Reducing the spacing between contacts may require reducing the amount of over-molded dielectric material around the signal conductors, which increases the difficulty of over-molding the signal conductors, reduces the insulating ability of the dielectric material, and/or reduces the structural support of the signal conductors provided by the dielectric material.
As the spacing between adjacent contacts is reduced, electrical interference and cross-talk produced between the contacts may increase, which reduces the speed and operating efficiency of the connector. There is also less available space for ground contacts or shields between signal connectors to reduce the interference and cross-talk. In addition, reducing the spacing between contacts may risk two adjacent contacts touching each other, such as when loading the circuit board in the socket, which could cause a short. Furthermore, reducing the spacing affects the impedance of the connector, and impedance generally must be tuned to match the operating environment.